are you really serious about this? If so the people at the
LFS really need to be edjucated on what they sell people. See Morish Idols have a very very poor survival rate in captivity. Plus they require alot of swimming room. 20 gallons is way to small for a morish. I wouldn't put it in anything smaller than a 75. You really need to take the fish back if you want it to live.